This invention relates to disposable single serve beverage filter cartridges.
A known disposable single serve beverage filter cartridge is disclosed in U.S. Pat. Nos. 5,325,765 and 5,840,189 (Sylvan et al), dated respectively Jul. 5, 1994 and Nov. 24, 1998. This beverage filter cartridge is comprised basically of an impermeable yieldably piercable cup-shaped container internally subdivided by a permeable cone-shaped filter into first and second chambers. A granular or powered dry beverage medium, e.g., roasted ground coffee, is stored in the first chamber, and the container is closed by an impermeable yieldably piercable lid.
During a brewing cycle, the lid and container bottom are pierced, respectively, by tubular inlet and outlet probes. The inlet probe admits heated liquid into the first chamber for infusion with the beverage medium, and the resulting brewed beverage passes through the filter into the second chamber from which it exits via the outlet probe for delivery to an underlying cup.
This known beverage filter cartridge has gained rapid and increasingly widespread acceptance, notwithstanding certain problems and disadvantages relating to its production and subsequent use that have persisted since its initial introduction.
For example, expensive and mechanically complex production equipment is required both to form the cone-shaped filter from a sheet of filter media, and to insert and secure the thus formed filter cone in the cartridge container. Slight deviations from close tolerances governing these steps can cause the filter to rupture or become dislodged from the container wall during the brewing cycle, resulting in contamination of the brewed beverage with beverage medium residue from the first chamber.
Because of its cone-shaped configuration, the filter has a limited extract storage capacity of less than 60% of the internal volume of the cup-shaped container. The unoccupied volume surrounding the filter component, commonly referred to as xe2x80x9chead spacexe2x80x9d, is largely wasted and thus adds disadvantageously to the overall size of the beverage filter cartridge. The additional head space also increases the likelihood of residual oxygen being left in the container, thus adversely affecting product shelf life. The cone-shaped configuration of the filter also limits the area available for lid puncture and inflow of liquid for infusion with the beverage medium.
Also, the side wall of the cup-shaped container is relatively pliable and thus prone to buckling as the brewer probes puncture the container bottom and lid at the onset of the brewing cycle. This can adversely affect the puncturing process, resulting in leakage around the probes.
What is needed, therefore, is an improved beverage filter cartridge which obviates or at least significantly minimizes the above-noted problems and disadvantages.
In accordance with the present invention, a beverage filter cartridge includes an outer container having a bottom with front, back and side walls extending upwardly to a peripheral rim surrounding an upper opening. The side walls are suitably contoured to minimize headspace, increase rigidity, and to define interior filter-supporting ledges located above the bottom and extending between the front and back walls. A planar filter element subdivides the interior of the container into first and second chambers, with the first chamber having a volumetric storage capacity of at least about 80% of the total internal volume of the outer container. Front and back edge regions of the filter element are secured respectively to the front and back walls of the container, and edge regions of the filter component are likewise secured to the interior ledges of the container side walls.
A beverage medium is stored in the first chamber, and a lid is applied to the peripheral container rim to seal off the upper opening.
The planer filter element is readily formed from a sheet of filter media, and is easily inserted and secured in place. The front and back container walls and the interior ledges of the side walls offer ample support surfaces against which edge regions of the filter element may be reliable secured. The contoured container side walls contribute advantageously to a heightened rigidity which beneficially resists buckling when the lid and container bottom are pierced at the onset of a brewing cycle.
The relatively large volume of the first chamber as compared to the second chamber translates into a more efficient package, making it possible to either increase the amount of beverage medium for a given overall cartridge size, or conversely, for a given amount of beverage medium, to decrease the overall cartridge size.
These and other features and advantages of the present invention will now be described in greater detail with reference to the accompanying drawings, wherein: